THE MAMMALIA— MAN AND BEASTS. 
67 
being general, it is confined to a very small proportion of the Animal Kingdom. 
If this superiority of size were characteristic of the sex, the loss of the reproductive 
organs during early youth ought to prevent it. The effect is, however, precisely 
the contrary, for castration, which brings the constitution of the male near to that 
of the female, is highly favorable to the growth of the former; these organs were 
therefore rather an obstacle to their development. 
This disparity seems to arise from the fact, that the nutritive powers of the female 
are, in the Mammalia, expended upon their offspring. The Cow', whoso weight is, 
perhaps, not one half that of the Bull, lives in a continual state of gestation or lac- 
tation ; and it is the same with the Ewe and She- Goat. Every Grazier is aware, 
that the young females cease to grow as soon as they begin to produce ; and that 
yielding milk is still more prejudicial to their growth than gestation. 
If we compare the Rurainantia and Herbivorous Cetacea with the Pachydormata, 
we shall find, that the young of the former consume much more milk than the young 
of the latter ; and, accordingly, it is in the two classes first mentioned that the pre- 
dominance of the male over the female in size b most decidedly marked. Indeed, 
the Pig is the only Pachydormata which is very prolific, and it is precisely in this 
Genus that the male more sensibly exceeds the female in dimensions. Of all the 
Rodentia, the Rats are the most fertile ; and the predominance of the male Rat over 
his female is more apparent than in any other of the Rodentia. 
Those blammalia which live upon Insects and Fruits, such as the Cheiroptera and 
Insectivora, do not exhibit the same difference of magnitude between the sexes as the 
proper Carnivora. The females of the former, from their situation, find an easy and 
abundant prey cither in the larva of Insects which hatch around them, or in the 
Fruits which fall and ripen near their retreats. The female of the latter is obliged, 
on the other hand, to pursue an alert and nimble prey, which often eludes her 
pursuit. Her young ones are not deficient in number, and she consequently loses a 
large quantity of nutritive power. From these causes, the male, who is always at 
large, and lives for himself alone, is wholly exempt; and hence the female of the Bat, 
the Hedgehog, and the Mole, is at least as large as the male, while the Lioness is 
smaller than the Lion. 
Among the Alarsupialia, where the females produce an embryo, or rudimentary 
foetus, which always travels about with its mother, and cannot keep her confined to 
a spot remote from her food, wo find that the female is at least as large as the male. 
With the Edentata and Tardigrade, the female is usually larger than the male. It 
is especially remai-kablo in the Ant-oaters, where the female, by the aid of her long 
tongue, an organ usually more developed in the female than in the male, enables her 
to catch the Ants, her prey, with a superior nimblericss and agility. 
Among the domestic animals, wlienever it happens that the female is made to work 
like the male, and that she is not compelled to submit to a continuous and depressing 
lactation, she does not yield to him in size. The She-Ass is as largo as the male ; 
the IHarc as the Horse; and the Dog is not larger than his female. In these cases, 
Man provides equally for their wants and necessities. 
Some Naturalists have considered the Polecat {Mustela foind) to be a domesti- 
cated variety of the Martin {Mustela martes). In the former, the sexes are of an 
equal size, while the male is greater than the female in the latter. With the com- 
mon Hare {Lepus timidus) the male is not so bulky as the female; on the contrary, 
with the Rabbit (E. cunicuius) the male is the larger of the two. This evidently 
may be traced to the superior fecundity of the latter species. 
We may easily see how the dimensions of animals should depend so much on the 
quantity and quality of their food, since all substances do not contribute an equal 
quantity of nutriment. Vegetable substances, which are mucilaginous and herbaceous, 
contribute much more powerfully towards the development of animals than those 
which are fibrous and of au animal nature. These are more favorable than acid 
substances; and the latter again surpass those which are saccharine. Thus among 
all the Mammalia it is the Herbivorous and proper Cetacea, the Pachydermata, and 
the Ruminantia, which attain greater dimensions than tho Carnassiers, and those again 
than tho Quadrumana and Edentata. Tho same thing may also be traced among the 
Birds, for the Waders {Grallai) and the Web-footed Birds {Palmipedes) become 
larger than the Birds of Prey {Accipitres)^ the latter arc in their turn larger than 
the Thrushes {THrdus)^ and these again than the Humming Birds {Trochilus). 
This advantage in respect to dimensions, to which a plentiful supply of food con- 
tributes, is unfavorable to reproduction, and hence acts ultimately against the species ; 
for the difficulties of procuring a suOlcient supply of food are always greater in tho 
larger than in the smaller species. Large species arc hence comparatively rare upon 
the earth, except where human industry has ministered to the insufficiency of their 
own resources. The smaller races of Goats and Sheep might maintain themselves 
without assistance in our temperate climates, but it would not be possible to preserve 
the larger races of these animals; and with still greater reason of the Horse, tho 
Cow, or tlie Ass. 
The superiority of the male over the female ought then to bo more apparent in 
the larger than in tho smaller species. With our Oxen and Sheep the difference 
's greater among the larger than among the smaller races. It is greater in tho Rat 
than in the Mouse. Tliis inequalily between the sexes would have been still greater 
in tho largest species, if the deficiency of nuti-ition sustained by the female did not 
l>ecome progressively less .iccordiiig as there exists a progressive diminution of fe- 
cundity. Among tlioae domestic animals, whose fismales supply us continually with 
the inequality becomes enormous in the largest species, because frequent milk- 
is still more unfavorable to development than a very great fecundity. Good Cows 
fatten during gestation, and become lean when milking commences, whatever may 
the quality or quantity of their food. 
I he primitive cause of this inequality of size between the sexes seems to show a 
tendency to return to an equilibrium ; and we may thence infer that there formerly 
<?xisted a greater dispai-ity between tho males and females of the Pachydermata than 
present, when wo find this disparity still existing among the Amphibia, which are 
®orc productive tlian tho Elephant, the Rliinoceros, and the Hippopotamus. 
Vlum the capacity of reproduction is extinguished, species arrive at their end. 
emay infer that it is chielly to the feeble powers of reproduction among the Pachy- 
dermata that we find so many fossil species belonging to this order which have no 
living analogues. Species, like individuals, decline and die, when they have attained 
the limit of their dimensions. 
From what has been said, it may easily be inferred that in those orders of animals 
where the male is usually monogamous, and shares with tho female the care of her 
progeny, he is not in general susceptible of that superior development beyond the 
female, as where he is polygamous. 
We have now seen that when two or more species of Mammalia resemble each 
other perfectly in their generic characters, their height is the same, or but slightly 
different. Those families, genera, or species, which inhabit the bosom of the ocean, or 
pass a part of their lives in tho water, arrive at a large size comparatively to the other 
families, genera, and species of the same group; and the increment of their dimensions 
is tho greater, all other things being the same, in proportion as their organization 
renders them more essentially aquatic. The genera with wings, or which live in 
trees, on the contrary, never attain to any hut very small dimensions. Those Mam- 
malia which are purely terrestrial, may be arranged in scries according to their di- 
mensions, very large in tho first, less in the second, and so on, that U, into herbivor- 
ous, carnivorous, frugivorous, and iniectivorous. In other w'ords, there always exists 
an exact co-relation between tho volume of tho animals and the volume or quantity 
of organized beings which they are destined, by the formation of their digestive 
organs, to consume. 
It has also been shown that there exists a constant relation between the height of 
the Mammalia and the extent of the places where they live ; the largest species 
inhabit the oceans, continents, or large islands; tho smaller reside in rivers or small 
islands. Even the I^Iammalia of a more extensive continent surpass in dimensions 
their analogues of a less extensive contment, and tho Mammalia of the Northern 
Hemisphere are larger than the corresponding animals of the Southern. In general, 
also, Vhough not always, the height of Mammalia resident in the mountains is inferior 
to that of the analogous animals residing in the plains. 
The preceding observations are true without exception in reference to the Mam- 
malia, but when applied to lower classes of animated Nature, they gradually lose 
their general correctness, and are finally lost when vre arrive at the lowest classes of 
all, in an infinity of exceptions. We, however, always find that when other circum- 
stances remain the same, the variations of size observable in any one class are always 
confined within narrower limits in proportion as that class is more natural. 
We have also seen that the size of tho body depends upon the quantity of nutritive 
particles which it is capable of retaining. The female would always attain a larger 
size than the male, as she is endowed with a greater power of absorbing nutriment, 
did she not experience the influence of certain counteracting causes which do not 
act upon the male. She has to submit to u severe lactation, in many cases to a fre- 
quent parturition, and is often compelled to undergo privations of food in her cares 
for her offspring. As these causes do not affect the male, there hence arise inequalities 
in their dimensions, or relations of volume, and these differences of size between the 
sexes, when they exist, depend upon the intensity of these causes. It must, how- 
ever, be admitted, that sometimes the relative sizes of tho sexes seem to be inex- 
plicahh by any of tho causes just enumerated, and in these cases wc must infer that 
diflcrences in the bulk of the sexes have been originally impressed upon the species at 
the moment of their creation. 
GENERAL REVIEW OP THE MAMMALIA CONTINUED. 
Phenomena of Nutrition among the Mammalia — Manner of obtaining their Food. 
That Animals can only die nourished by substances which have once lived, in other 
words, by other Animals or by Plants, we have already had occasion to explain. 
Some persons havo hastily concluded, from imperfect observations, that animals can 
nourish their bodies with inert mineral substances. This opinion is, however, erro- 
neous. That yellow earth which the famished Wolves havo been seen to swallow in 
their rage., serves but to deceive the intensity of their hunger. The Mollusca do not 
devour tho fragments of rocks or old wood which they destroy or perforate, nor do 
Birds digest those hard mineral substances which are sometimes found broken or 
pulverized in their gizzards. 
The food of the Mammalia is very various, since it takes in all other animals and 
vegetables. There always exists a certain correspondence between the degree in 
which the organs of an animal are complicated, and the nature of the food which it 
consumes ; for it has been generally remarked, that the simplest beings always require 
tho simplest food. The Tiger feeds on a living prey, the Wolf upon carcasses, the 
Otter upon fish, the Hog upon roots and animal food, tho Myrmecophaga upon 
ants, the Apes upon fruits, the Roilentia and Ruminantia upon simple herbs, Muu 
and tho Bear upon almost any thing. 
Thus we may remaik among the Mammalia the greatest diversity in their tastes 
for food. While in some tho nutriment wholly belongs to the Animal Kingdom, in 
others it is as entirely confined to the Vegetable. Others again, whoso iiourishmeTit 
is mixed, seem to avail themselves at once, or indifferently, of tho produce of either 
Kingdom. These varieties are usually expressed by tho terms sarcophagous or car- 
nivorousy phytophagous or herbivorousy polyphagous or onmivorous. 
These first differences of animals in respect to their food, presuppose or draw 
along with them certain other differences in respect to their organs. A carnivorous ani- 
mal has more teeth than an herbivorous one ; these teeth arc more unequal, more fitted 
for teai'ing, and more trenchant like a saw. llis jaws ore more free, more powerful, 
and moved by larger and more vigorous muscles ; his stomach is not so large, and its 
sides arc thinner ; his intestines are shorter, and proceed w'ithiu a slimmer form 
through a less capacious abdomen, llis limbs are also differently disposed than in 
the herbivorous animals, as the voracious instincts require instruments at once fitted 
for agility and destruction. 
Many cai'nivorous animals will only devour a living prey, which leads them to 
